Hydrolysis

Hydrolysis is a chemical process in which a molecule is cleaved into two parts by the addition of a molecule of water.

In a hydrolysis reaction that involves breaking an ester link, one hydrolysis product contains a hydroxyl functional group, while the other contains a carboxylic acid functional group.

One fragment of the parent molecule gains a hydrogen ion from the additional water molecule. The other group collects the remaining hydroxyl group from the water molecule.

In other hydrolysis reactions such as hydrolysing the peptide links of amino acids only one of the products, the carboxylic acid product, has a hydroxide group derived from the water. The amine product gains the remaining hydrogen ion.

Hydrolysis is distinct from hydration, in which water molecules are added to a substance, but no covalent bonds are broken.

Hydrolysis can be considered as the opposite of condensation, in which two fragments are joined for each water molecule produced. As hydrolysis is a reversible reaction, condensation and hydrolysis can take place at the same time the position of equilibrium determining the amount of each product.

See also: Biopolymer, Condensation polymer